The Occupational Studies Section (OSS), EEB, EBP, DCE, NCI, conducts a broad program of investigations to identify and evaluate carcinogenic factors. This contract will support data collection activities for 20 to 25 projects. The studies supported by this contract are designed by NCI Investigators who also analyze and interpret study results. The Contractor must be capable of providing support for a number of studies conducted simultaneously in widespread geographic regions of the United States and other countries. A critical capability is to be able to respond quickly to changes in priority and to supply support to urgent new efforts. A sample listing of some of the studies which may be supported by this contract are: -- Interdisciplinary studies of 300 brain cancers, 300 stomach cancers and 500 controls in Nebraska with examination of risks from agricultural exposures, diet, environmental pollution, p53 mutations, and Helicobacter antibodies. -- A nested case-control study of leukemia and brain cancer among embalmers (150 cases and 350 controls) designed to evaluate specific work practices and exposures that may account for excesses of these cancers. -- A cohort mortality study of 30,000 lawn care workers designed to evaluate cancer risks from exposure to herbicides and insecticides. -- A cohort study of 3,000 employees of County Noxious Weed Departments in Kansas who have heavy exposure to herbicides. Cancer mortality and incidence will be evaluated as well as biologic markers of immune system aberrations to investigate mechanisms of action of these chemicals. -- A cohort mortality study of 25,000 chemical workers exposed to acrylonitrile that includes a detailed exposure assessment component and interviews with a 10% sample to obtain information on tobacco use. -- A cohort mortality study of 8,600 firefighters in Philadelphia. -- Extended tracing to ascertain more recent mortality among 25,000 workers exposed to formaldehyde, 8,000 copper smelter workers, 11,000 dry cleaners, 6,000 U.S. Coast Guard marine inspectors, and 45,000 workers in the grain industry.